Hello Everyone: It's been a long time since I last posted in here, for that I apologize, but I truly have a problem and want to confirm my diagnosis. My '98 Mustang's temperature gauge is nuts! I put the heater on in the car and after a while it goes to the middle of normal with the hot air from the heater kicking on. Then...........all of a sudden (after say one minute) the air from the heater gets colder (ambient outside temp?) and the gauge goes all the way to the tick mark/bracket after NORMAL (right before High). It does not/has not gone to high yet. It is my assumption that my thermostat is going out. Does this sound right? Only recent work that has been done to the car was a Seafoam treatment about a month ago and an oil change in the last three days. No other work has been done for over a year. Also as an FYI my car currently has 138,000 miles on it. THANK YOU very much for anyone that can shed some light on my problem. Hello all just noticed something. The gauge only goes up in the morning. Today while driving home from work I looked at the gauge, nothing amiss. Put on the heater, no problem, hot air coming out fine?! Is this indicative of a stuck thermostat when going from cold (night) to hot (daytime)? Again, thank you for any help you can provide.
did you check the prestone level. if prestone is full then get it to a mechanic soon. Running your car at that temp will have definite effects on the motor. Could also be head gaskets.
My suspicions were correct on this one. Replaced the thermostat and all is well. Thank you for those who replied to my post.
